Adjustable helmets are already known. As a general rule, the conventional adjustable helmets achieve adjustability through the utilization of fastening members which must be unscrewed to permit adjustability, and then screwed tight to lock the parts in relative position after adjustment.
It would be highly desirable to provide an adjustable sports helmet in which adjustment could be accomplished very quickly and manually in the field, so to speak, without requiring hand tools. For example, if a young hockey player should borrow his brother's helmet and then find, after he has begun playing a game, that the helmet has been adjusted too small or too large for his own head, it is very inconvenient for him to take the time necessary to find the appropriate tool, unscrew the fasteners, adjust the helmet, and then screw the fasteners tight. It would be far preferable if the player could, while still having the helmet on his head, simply accomplish a manual operation which would allow adjustment of the helmet to a different size.